First of all, it is necessary to understand the different types of drug testing methods, how they work, and also the various parameters which affect the results of a drug test.
Types of Drug Testing
Drug testing is usually carried out on urine, blood, saliva, hair, sweat and breath (this is usually for alcohol test).
Out of these, courts usually prefer the urine test as being the most reliable and accurate, compared to tests on other bodily fluids. Blood tests are reliable, but courts do not prefer them since they are invasive.
Factors Influencing the results of your Drug Tests
Factors which often determine how much you ingest, and how long the traces of drugs remain in the body are:
- Your height
- Weight
- Fitness levels
- Metabolic rate
- How often you smoke
- What quantities you smoke
- How long you have been smoking
- Any other prescription drugs or medications, or even foods which you may be ingesting.
Accuracy
No drug test is totally infallible. Poor quality or contamination in drug testing labs has revealed rather high error rates in some of the results given by them. ‘False positive’ often show up. This is why it is sometimes possible to pass a blood drug test and then fail a urine drug test, or the other way, too.
To provide essential safeguards, the Department of Health and Human Services issued detailed and mandatory guidelines (SAMHSA guidelines). These guidelines will assure security of the sample, prevention of tampering, prevention of dilution and chain of custody, along with a back-up testing, in case of positive results. If followed properly and in detail, there is greater chance of correct and accurate results.
How long do the drugs stay in your system
- Cocaine and other opiates usually wash out of your system in 2 to 3 days.
- In marijuana, it stays longer depending upon whether you are a regular user and how many times you smoke it in a day.
It is the main chemical in marijuana, called THC, which remains in the system for very long periods since it gets stored in the fatty tissue of various organs.
- In frequent marijuana users (those who smoke several times in a week), THC by-product from marijuana can remain in the blood for 2 or more weeks after the last week, while it remains in the urine for 3 months.
- For infrequent users of marijuana, THC by-product can remain for 2 to 3 days after the last smoke, while it remains in the urine for at least 10 days.
That is why it is sometimes possible to pass a blood drug test but fail a urine drug test.
Submitted by M H on January 27, 2010 at 04:14